The invention relates to a device for the display or projection of images or similar information.
Display devices such as cathode-ray tubes and liquid crystal display units have a transparent front wall, most usually made of glass. The image is formed on one side of this wall and is observed on the other side.
The quality of the image observed depends on the physical properties of the material of the wall and on its state, notably the state of the external face.
In the same way, the projection device usually has an output objective and the quality of the projected image may be lowered if the external surface of the projection objective is in poor condition.
The invention can be used to reduce dependence on external disturbances of the state of the external surface of the transparent front wall of the display device or the state of the external face of the projection objective.